The Royal Society Winton Prize is excellent: http://www.theguardian.com/books/royal-society-science-book-....
Some personal favourites:
The Incredible Unlikeliness Of Being by Alice Roberts is a wonderful book that describes how a human being develops from conception to adulthood in minute biological detail.
The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography by Simon Singh is fantastic, if a little out of date by now.
Cosmos: The Story of Cosmic Evolution, Science and Civilisation by Carl Sagan.