The Melt modifier lets you apply a realistic melting effect to all types of objects, including editable patches and NURBS objects, as well as to sub-object selections passed up the stack.
Options include sagging of edges, spreading while melting, and a customizable set of substances ranging from a firm plastic surface to a jelly type that collapses in on itself.
1. Modify panel - Make a selection. - Modifier List - Melt
2. Make a selection. - Modifiers menu - Animation - Melt