Pop-ups means advertisements opening in new Firefox windows, are you really talking about those? If so - Adblock Plus can block advertisements but it cannot prevent Firefox windows from opening. A good pop-up blocker is actually built into Firefox. If the built-in pop-up blocker fails for you, this experimental extension might help: https://addons.mozilla.org/addon/83098
(use at your own risk).
But if you are actually talking about advertisements, the filter "||abc.com^" will block everything from the domain abc.com. For more info: https://adblockplus.org/en/filters