Why do people pop their gum so obnoxiously?

Ok, so I was just in my living room doing some homework and kinda listenin to some music, and my mom was in the kitchen sitting down doing some paperwork or something, and she was just constantly popping her gum! At first it didn't bother me, but about 5 minutes later, it started to really get on my nerves. I didn't want to ask her to stop and make her angry so I just left, and she was wondering why. Lol. Why do people pop their gum so much?!