To become disintegrated, to break into parts or pieces.
To come to ruin, to fail. To lose (a person's) composture or self-control
Used other than figuratively or idiomatically: see come, undone; to become undone or unfastened.
Of salts and minerals, to crackle when heated, indicating a sudden breakdown of their particles.
To roast (a salt or mineral) until it stops crackling in the fire.