estimated taxes due to scholarships

My college student had to pay  around $1200 in taxes due to a large scholarship/grant amount that exceeded the educational expenses by a lot. He also had a small (2K) SE income which he won't have this year. After we filed his taxes and printed the paperwork, I see that it requires him to make estimated payments of $300 every quarter. I am surprised because he doesn't have any income and this year we paid his taxes from the refund we got since he is our dependent. I was wondering if this payments are set and mandatory, can't we just pay the taxes at once when we file next year? We don't even know if he'll receive the same amount in scholarships since it's still too early to know about the new school year starting in the fall.

Does anyone know more about how exactly this is supposed to work or have any experience with that?

Thank you.