Hello,
what is likely is that the browser has remembered that you have accessed this page, and when eg. opening new tab or writing into address bar, it access the page.
You can either clear your browser's history so that the browser forgets about the infected page, but it is also possible (and simpler) to mute further popups for this URL forever; this can be done from the popup itself.
Kind regards,
Ondrej Kolacek