If you use TortoiseHg:
Windows users can use Windows Explorer and view the revision history by right-clicking on the file.
For Linux users, you can do it within TortoiseHg but it took me a while to figure out how. You need to right-click on the desired file and select "File History". However, for some mysterious reason, the file needs to be unaltered. Furthermore, to find the desired file there are two options:
In ### revision set query###
one can type:
file("**<myfile>")
The double ** are necessary to search directories recursively. This gives you immediately an list of all repositories in which the desired file was changed.
Alternatively, next to the ### filter text ###
click first on the question mark sign and select "clean" to see all files in the repository. Then inside the ### filter text ###
box you can narrow down the number of files shown.
Alternatively, Linux users can do it from a terminal as suggested by Geoffrey Zheng above:
thg log file