As Lot leaves Sodom the angels warn him (Genesis 19:17):
And as they brought them out, one said, "Escape for your life. Do not look back or stop anywhere in the valley. Escape to the hills, lest you be swept away." (ESV)
His wife didn't listen (Genesis 19:26):
But Lot's wife, behind him, looked back, and she became a pillar of salt. (ESV)
That is an unusual punishment. She didn't get swept away like verse 17 said and she didn't get fire and sulfur like Sodom. Other times people were killed with fire (Nadab and Abihu), earthquake (Korah), swords (lots), or not specified (Able), but nobody else died by salt.
Is this just random, or did it mean something to the original readers of this book? I am asking about salt and about it being a pillar.