So if my player was looking at the water they'd see it boiling and bubbling up...?
Yea... Use some particle effects could easily do the steam/bubbles... For the water moving itself... Personally, I'd go in to 3ds max and just do a noise modifier, auto animates and everything, and then just export the animation and use that, so in other words, you can just animate/model it....
But besides that... You could (If you have pro version), you can have a movie texture of boiling water and have that actually do it...
Besides all that, I can't see any other real way, you're going to have to do an illusion kinda thing.