There is some difficulty in how the term nation is defined and used here.
Mainly adding to Alex' answer:
It might be argued that Austria was an entity that was in modern times forced out of its home nation (whatever 'Germany' was at that time) three times additionally to what Alex identified!
Austria has been a member of the Holy Roman Empire from its inception.
- It was forced out of this Reich first by Napoleon in 1806
- Then a German Confederation was established as a successor with Austria as a leading power. But as that construct slowly developed into the German Reich Austria was again forced out by the by Bismarck in ~1866–71,
- When Austria-Hungary itself collapsed in 1918 the allies after World War I in 1919 forced Austria out of Germany again:
On November 13, 1918, German-Austria asked Germany to start negotiations of union and on November 15 sent a telegram to President Wilson to support union of Germany and Austria. This was grounded in the view that Austria had never been a nation in the true sense. While the Austrian state had existed in one form or another for over 700 years (dating to the Holy Roman Empire), its only unifying force had been the Habsburgs. Apart from being German-inhabited, these Lands had no common "Austrian" identity. They were Habsburg-ruled lands that had not joined the Prussian-dominated German Empire after the Austrian Empire lost the Austro-Prussian War.
On March 12, 1919, the Constituent Assembly re-confirmed an earlier declaration that German-Austria was a constituent part of the German republic. Pan-Germans and Social Democrats supported the union with Germany, while Christian Socialists were less supportive.
During spring and summer of 1919, unity talk meetings between German and Austrian representatives continued. All this changed after June 2, 1919 when the draft peace treaty with Austria was presented, which demonstrated that the Western Allies were opposed to any union between Germany and Austria.
–– Wikipedia: Republic of German-Austria # Failed union with Germany
And again in addition to Alex: Serbia was the dominant state of Yugoslavia and tried very hard to not only remain in this state, but also to be that state.
As the Yugoslav Wars raged through Croatia and Bosnia, the republics of Serbia and Montenegro, which remained relatively untouched by the war, formed a rump state known as the Federal Republic of Yugoslavia (FRY) in 1992. The Federal Republic of Yugoslavia aspired to be a sole legal successor to the Socialist Federal Republic of Yugoslavia, but those claims were opposed by the other former republics.
The United Nations also denied its request to automatically continue the membership of the former state. In 2000, Milosevic was prosecuted for atrocities committed in his ten-year rule in Serbia and the Yugoslavia War. Eventually, after the overthrow of Slobodan Milošević from power as president of the federation in 2000, the country dropped those aspirations, accepted the opinion of the Badinter Arbitration Committee about shared succession, and reapplied for and gained UN membership on 2 November 2000. (From 1992 to 2000, some countries, including the United States, had referred to the FRY as Serbia and Montenegro.) In April 2001, the five successor states extant at the time drafted an Agreement on Succession Issues, signing the agreement in June 2001. Marking an important transition in its history, the Federal Republic of Yugoslavia was officially renamed Serbia and Montenegro in 2003.
–– Wikipedia: Yugoslavia # Breakup