I saw this in the Total Training Tapes...
Use a zig-zag cutout of red/yellow/orange (like pointy mountians).
Use the wave warp on it a little. Then on a black solid, apply
the foam effect. Make the bubbles big and slow. Then blur the
heck out of it. Pre-comp this with the cutout. Then put it over top
your text. There is alot of fine tuning involved, but it works.