Anyway you can tell what's behind plasterboard to frame pictures?

Sorry if it's the wrong sub Reddit...

I've a lot of pictures frames I want to hang. The problem is, the galring empty spaces in the house are above a good many radiators.

I'm told the wall is made from plasterboard, and so it's difficult to tell what's behind it compared to material like timber.. I don't want to burst a pipe, so is there a way to tell? - or are you best hiring someone with the know how?...

Silly question, I know.