I have no idea why people down-voted you, this is a perfectly legitimate and pretty good question; some here are just jerks...

Yes, but rarely. And mostly at the end when the star is at its hottest in the center. I don't have numbers on how often it actually happens, but it definitely does.

At the most extreme end in particular, when a star goes supernova (not all do) it collapses so hard to its center that this creates extreme pressure and releases absurd amounts of energy. This fuses iron and all the other stuff beyond all limits; the energy is almost irrelevant, we are talking about hundreds of Earth masses(!!!) as pure energy. This is one of the two processes that creates the elements beyond iron in the amounts we find them (the other option are collisions of neutron stars).