I teach mining geology and "Other courses". One of my favorite popularly written books is DNA by James Watson, (one of 3 wcientists awarded the Nobel prize for first describing the structure and bonding of DNA). His book is written from a valuable distance and is focused on the entire scope of DNA(what it is, who did a lot of work on it, what it does, and how we know). Its very accessible without being childish in it oresentation.
T Rex and the CRATER OF DOOM, by Walter Alvarez is a good discussion of the evidence that surrounded the discovery of a meteorite impact crater (and its consequences to ancient life),
Its written almost as an adventure tale.
The FEYNMAN LECTURES are also good but they presume a certain proficiency in math, even though they are popularly written.
EO WIlson-The DIVERSITY OF LIFE, IS a treatise, popularly written, about the web of life on the planet. WIlson is one of the worlds leding entomologists. He uses his specialty of the study of ANTS as a mere jumping off point to investigate life and its rise on earth.
There are others in each field but these are a few I like and have read more than a few times.