Additional Information pop up box next to a variation in drupal commerce
I was surprised that there wasn't a module that did this so I've created one.

It is only a sandbox project at the moment as I'm still waiting to get approved to create full projects.

Sandbox page

It can however be downloaded from here. You will then need to extract the .tar.gz to a .tar, and then extract that to a folder called "2240445-cbcb2b4" and then rename that folder to field_info_popup (Phew!).

I've tested it with all the core field types and seems to work fine but if you do find any bugs then they can be posted here.