Finishing Sentences

I know you're not supposed to complete people's sentences but I can't help myself when someone is talking about something science-y and I want to let them know I'm not a fool of a took on the subject. I was talking to some stranger in town about nuclear bombs and he was trying to explain that a nuclear bomb is not an explosion rather an _____. Where I completed his sentence with "[...]implosion, a domino effect towards the center".