“But his wife.” We know nothing about Lot’s wife. We don’t know when, where, or who he married.
“looked back from behind him.” It was customary for the woman to walk behind her husband, so it is quite possible that Lot never noticed that his wife was not following, but had stopped to reminisce over all they had left behind, and she was caught up in the destruction.
“pillar.” This is the only time in the Bible that this word is translated as “pillar.” Otherwise, it refers to a soldier, representative, overseer, governor, or even a “garrison.” This is not the normal word for “pillar.” So in the context of a military aspect, like a soldier or a non-military context like “representative,” it would be possible that she was a pile of salt, a “witness” to what happens when you ignore the warnings of God. The suggestions that she suddenly became a statue of salt seem incorrect. The “statue” idea comes from the word “pillar,” but that translation is more than suspect, as we saw above.