(Phil, aka Stevie) IPA (chemists' term for isopropyl alcohol) won't shift chewing gum. That stuff is little better than an organic version of Blu-Tak, i.e. resistant to almost anything. Try a blowlamp. This post is from penelope, who has broadened her portfolio, as they say.
Bubblegum will often yield to a stint in the deep freeze. Oh, penelope already said that. To keep with the theme of chemical application: Try pouring a little liquid nitrogen on the bubblegum (and anything else your scientific interest in catastrophic failure under cryogenic shock lights upon - pens, fruit esp. grapes, and rubber gloves are classic favorites) and carefully prying it off. Use At Own Risk - not responsible for shattered glasses, pullovers, cricket bats, shoe-soles or whatever.