Can I leave Thailand during my single entry visa validity and return for a 30-day stay?

hey guys, I've been here on exchange and my single entry visa expires january 15th and I cannot extend it any longer, however I was planning on staying till january 31st, so is it possible for me to leave thailand in the first week of january (going to hong kong 4-7th jan) without re entry permit so my single entry visa expires when I get back, and I get the 30 days to stay here as tourist till the end of the month? thank you so much for helping me out