One group of scientists think an extremely energetic supernova observed last year may have been caused by an exotic form of stellar collapse involving antimatter. The thinking goes that if a first-generation star was extremely massive, on the order of 150 times the mass of the sun, the high temperature and pressure would create conditions ideal for converting some of the star's photons into pairs of electrons and their antimatter opposite positrons*. This would result in a pressure drop, making the whole star unstable, eventually causing runaway nuclear reactions that rip the star apart and spew who knows what sort of exotic stuff into space.
At least, that's one hypothesis. Other scientists, of course, disagree. The article doesn't mention what sort of predictions are made by this team, but presumably there are some which can be tested in the future.
Ain't physics fun?
* I think, although the article does not explicitly state, that this is a natural case of inverting Einstein's E=mc2. Unfortunately my algebra is so atrophied I can't even write the equation for turning energy into mass. Sue me.