Next time you get this, can you copy the link of the page you are taken too and send it to us?
Did you install any other apps on your phone just before you started noticing these?
The only app I recently installed is one for my Chamberlain garage door opener "myQ". I doubt that has anything to do with it. I read on the web it's best not to click on these " might be infected" links at all and to close entire page, so I don't know if it's safe to do so?