Not sure how to explain this.

Make a 2x2 wide column with magma blocks at the bottom and surrounded by glass blocks.

GGGG
GMMG
GMMG
GGGG
(looking down)

Add water and you get bubbles. Looking from the side it glitches so you no longer see the water and just see the bubbles. It comes on and off as you walk round the column. Water remains visible at the very top.