After clarifying the (unclear for me) meaning of "popular science" (thanks Sasho :-) I propose:
Title: Winning Ways for Your Mathematical Plays (4 volumes)
Authors: Elwyn R. Berlekamp, John H. Conway, Richard K. Guy
Description: it can be considered a compendium of information on mathematical games (tons of games are analyzed: coin and paper-and-pencil games, Soma, Rubik's Cube, mechanical wire and string puzzles, sliding block puzzles, magic squares, Life). It is easy enough to please any fan of recreational mathematics or simply anyone who is interested in games and how to play them well; but I think that it has also been a source of inspiration for many deeper results in combinatorial game theory.
It is not a book, but I think that the Martin Gardner's 'Mathematical Games and Recreations' column for Scientific American must be cited.
Resource: The 'Mathematical Games and Recreations' column for Scientific American
Author: Martin Gardner
Description: for 25 of his 95 years, Martin Gardner wrote 'Mathematical Games and Recreations', a monthly column for Scientific American magazine. These columns have inspired hundreds of thousands of readers to delve more deeply into the large world of mathematics. He has also made significant contributions to magic, philosophy, debunking pseudoscience, and children's literature. Many Martin Gardner's books are collections of informative extracts from his Scientific American column (e.g. Fractal Music, Hypercards and More...: Mathematical Recreations from Scientific American Magazine, Wheels, Life and Other Mathematical Amusements, ecc. ecc.).