I do not think there is a part of science that is not interesting. Everything you do in science (good and bad ideas) will eventually lead to a final result. And I think that the moment you get that final product/result you will feel really good.
I find the most interesting part of science is when I apply the principles to a real life situation – like look my calcs say this rope can hold 10 tonnes and it does! Or this motor should be powerful enough to rotate this 100t steel basket .. and guess what most of the time it does!