A bug with water

I was play with the new fireworks in the water and I was setting them off in the water and came out of the water a found that the water was gone when I got out but came back shorty after the firework went off. P.s.I was in a cave and the firework was on the ceiling and the water would be gone then reappear.

I thick the water should be there the hole time.

The water was gone.

what happen
1.I made a firework
2.Set it off in the water
3.Flied out of the water
4.Look some what up (could see the water and the ceiling)
5.Water was gone and came back.