Lot's Wife Remembered

Genesis 19:26 - But Lot's wife looked back, and she became a pillar of salt.

I wonder why "a pillar of salt." Obviously her looking back (after being told not to) was a sign that she wanted to be back in Sodom or that she loved all the stuff she left behind more than what God had in mind for her on the road ahead. She paid for this choice with her life. But why did she turn into a pillar of salt as opposed to "simply" falling down dead due to heart failure or something more ordinary?

Perhaps this was so that we would talk (and write and read) about her as a warning not to have similar thoughts and feelings about the evil things in our past and as a reminder to keep looking forward to the good that God has in store for us in the future either here on earth or later in heaven or both.