‘But his wife looked back from behind him and she became a pillar of salt.'
The final footnote increases the tragedy for Lot and warns against complacency. His wife was possibly a native Sodomite and could not bear to leave her home and family. As they hurry on she lingers behind, refusing to stay with them, and perhaps even turns back to return to her family home (‘looked back' is a euphemism. It is not to be taken strictly but as signifying a heart that looks back resulting in further action). She does not believe Yahweh and she does not want to leave her people. We are to understand that Sodom is still in her heart for Yahweh allows it to happen. He knows the thoughts of the heart. Had she been like Lot she would have been spared for Abraham's sake. Whatever the case her delay means that she is caught in the conflagration and is overwhelmed by a deluge of bitumen.
“She became a pillar of salt.” By being overwhelmed with a deluge of bitumen which would soon dissolve her body.