I would highly recommend Biostatistical Analysis, 4th Edition by Jerrold H. Zar (http://www.amazon.com/Biostatistical-Analysis-4th-Jerrold-Za...). Don't let title mislead you. This book does does an excellent job presenting the background, development and fundamentals of a wide variety of statistical methods. The treatment is very thorough; if you can work through the entire book, you would certainly possess a good understanding of the topic. What I appreciate most is the comprehensive treatment of the limits of each method/test, allowing you to apply them (or not) with confidence.

Another classic is The Use and Abuse of Statistics by W.J. Reichmann. The treatment is not nearly as formal, but it is still a worthwhile read.