here's a cool tutorial for a melt on text effect. you could reverse the process for a melt off effect, or just use the technique to create your own melted text effect...
http://www.ayatoweb.com/ae_tips_e/ae21_e.html
he uses fractal noise and the displacement map for the basic distortion. it's not exactly a beginners tutorial, his english is a bit broken and he doesn't always give precise details (he expects some trial and error on your end), but it may be quite helpful to you.
Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW