Bubble Hair
People will tell you that their bubble hair 'just happened', quite suddenly, after they had been doing the same things to their hair for a long time. Then all at once they noticed tiny 'bubbles' in the ends of their hair.
Invariably, bubble hair is caused by some kind of heating appliance, most often curling irons.
These operate somewhere between 120 and 180 °C, roughly speaking. Water boils at 100 °C. If a hot curling iron is put on to wet hair, it boils the water inside the hair. The boiling water softens the keratin of the cortex; then the steam from the boiling water expands and forms tiny bubbles inside the hair. Eventually the hair breaks off, either at or somewhere near a bubble.
Every woman who has used curling irons knows that they work better on some days than others. One day she may have them just a little hotter than usual: that might be just enough to cause bubble hair, and for the affected hair to break off.
Although the sufferer usually claims that her hair was perfectly normal until she changed the hair product she was using, further enquiry always uncovers a history of increased or excessive cosmetic treatments. Usually bubble hair happens to people who are doing a lot of styling to their hair at home. And it is always, always associated with the use of heated appliances on damp hair.