It would have 'melted your heart' [=it would have filled you with compassion, sympathy, etc.] to see her lying in that hospital bed.
Her anger 'melted away' when she saw that he was truly sorry.
He seemed to 'melt into' thin air. [=he seemed to disappear]
(..) Come on. Holy shit! I need a vacation. Is it dead? Terminated. Will this melt in there? Yes. Throw it in. Adios. And the chip. It's over. No. (..)1991 Terminator 2: Judgment Day