It's certainly an interesting idea. The thing is, extremely massive black holes don't explode - their gravity is just too high for that kind of large scale energy release. That being said, they can and do evaporate over time - virtual particles, which appear and disappear continuously in a vaccuum, appear near the event horizon of a black hole, and gain just enough of a boost from its gravity and in the right direction that they become real particles. This steals a bit of energy from the black hole, and causes it to lose mass. It's known as Hawking Radiation.

As for where it all came from in the first place, I think one of the prevailing theories is that the universe is basically a virtual particle; a quantum fluctuation, that as long as the net energy gain remains zero, our universe may continue to exist as it is. I *think* that's how the theory goes.