We have two cats that are obsessed with bread. Can't leave any out without them fairly quickly chewing through the wrapping to eat the bread. We've had quite a few cats over the years, but have never seen that type of weirdness before.
My parents cat has an absolute vendetta against bread in a bag. He doesn't eat anything and bread or bags alone are utterly ignored, but if there is bread inside of a bag, it will be annihilated.