ideas on thanking bf

I had been feeling so down because I had to pay for my spring semester of school tomorrow but was lacking a very high amount of money needed. I was sure I'd have to miss this semester of school but my boyfriend paid for it as a surprise. I have no idea how to thank him. Any suggestions on how to thank him? Like something sweet I can do or anything idk. I'm obviously going to pay him back as soon as I have the money even though he does not want me to. It feels so weird to know he paid for it. He says he cannot see his girl miss a semester of school & that he will always have my back. He is so sweet! I'm at lost for words.