I can see it's been a while since you posted this. Nonetheless I'm pitching in.
Generally 참을성/인내심 is a 1:1 equivalent of 'patience'. But in this case you are directing it to a teacher, and I think in Korean culture when you thank someone for taking their time for you in a patient manner, you don't often go and compliment their persistent character: you just thank their act. Because you cannot be sure that their act of being patient is whether the result of their patience, or fondness toward you, or just their work ethic, or passion. So when a teacher attends to students thoroughly out his/her passion in teaching, and you compliment their patience, who knows how the teacher would feel?
끝까지 들어주셔서 감사합니다.
지루했을 텐데, 끝까지 들어주신 점 감사드립니다.
항상 찬찬히 가르쳐주셔서 감사합니다. (찬찬히 -is when someone takes their time and do something very thorougly)
선생님, 항상 자상하게 가르쳐주셔서 감사합니다. (자상하게 normally passes for "kindly" but its Kanji/chinese character are 자(in detail), and 상(thoroughly). Someone is kind(자상) when he/she is thorough in explaining in detail.)
선생님, 늘 세심하게 가르쳐주셔서 감사해요. (세밀- 세 means "fine(delicate)", 심 means "heart", so 세심하게 is "an attitude of caring, and being observant and not being neglectful).
바쁘실텐데 늘 시간 내 주셔서 너무 감사합니다.
I guess you have already thanked your teacher, but hope this helps when you thank him/her again in the future)
바쁜데 읽어줘서 감사!