Is it normal to pay to quit?

I got hired at a high end salon as an apprentice and I’m starting their training program next week. It’s $25 a class and it’s 12 weeks, one class a week. I was told that I’m going to have to sign a contract that my boss is going to require me to pay her back for her time if I quit during the program. If I stay then I don’t have to pay. I’ve never heard of this before and wanted some opinions. She told me she’s had stylists start her training and then quit halfway thru and she just wants to ensure her time and the money she spent on the education she’s sharing with us isn’t being wasted. On one end it makes sense but on the other, it seems fishy bc I’ve never heard of that before with any kind of job.