Can cotton bar towels washed with bleach spontaneously combust with high heat from a dryer?

I owned a restaurant where this happened more than one time. The towels were taken from a very hot commercial dryer and placed in a plastic paint bucket. The left over bleach and heat seemed to be the culprits. I now have a friend who claims this is scientifically impossible and someone must have ignited a spark in the towels. I need proof and Google only speaks to this happening with oil soaked rags.