Are we supposed to post our own thoughts?? I don't know so I am writing this…x_x
I think the balloon didn't pop when it was full of water because the water was sort of blocking against the match pushing it. Does that make sense? Like, when the match was next to the balloon filled with air, the balloon didn't have anything inside so when the match touched it, it exploded because it was empty. So the water was sort of "protecting" the inside.
Anyway, that's what I think. I'm probably wrong :(.