What I'm trying to do is brighten an explosion so that it gets extremely bright and then ends up washing out the whole picture which I will then use for a transition. Is there any way to do this?
There are lots of controls under Effects>Color Correction that may be useful. You could also stack up the layers and use the add or screen blend modes. If you are really jacking things up it's better if you set your project settings to 32 bit.
This is all basic AE color grading stuff that you should spend some time learning and understanding. The best technique depends entirely on your shot and how realistic you want the effect to look.
I am new to Ae, so it'll take some time. But thank you.