When you say non-fiction, do you mean pop science books? I'd be very surprised if you grokked a math, hard science or programming book after just reading the first third introducing the subject.
Pop science, business books, political books, that sort of thing - proper graduate-level math and science textbooks definitely have plenty of content. Sometimes those can even be on the opposite side of the spectrum, where the focus is too much on the equations and not enough on the conceptual.
