We've recently seen the largest explosion ever recorded: a supergiant star two hundred times bigger than the sun utterly obliterated by runaway thermonuclear reactions triggered by gamma ray-driven antimatter production.  The resulting blast was visible for months because it unleashed a  cloud of radioactive material over fifty times the size of our own star, giving off a nuclear fission glow visible from galaxies away.

The antimatter annihilates with its opposite, as antimatter is wont to do, but the problem is that the speed of antimatter explosion - which is pretty damn fast - is still a critical delay in the gamma-pressure holding up the star. The outer layers sag in, compressing the core more, raising the temperature, making more energetic gamma rays even more likely to make antimatter and suddenly the whole star is a runaway nuclear reactor beyond the scale of the imagination.  The entire thermonuclear core detonates at once, an atomic warhead that's not just bigger than the Sun - it's bigger than the Sun plus the mass of another ten close by stars. 

The entire star explodes.  No neutron star, no black hole, nothing left behind but an expanding cloud of newly radioactive material and empty space where once was the most massive item you can actually have without ripping space.  The explosion alone triggers alchemy on a suprasolar scale, converting stars' worth of matter into new radioactive elements.

And we saw this.  This really happened.  

Brutally awesome.