@cyanide30 Try adding cryptorank.io###mobile-popup to your content filter. You can do this by going to Settings → Shields → Content Filtering, then typing or pasting it in the Create custom filters area. It should work, though I still notice the popup for a split second when I first navigate to the site (at least on my iPhone).
@fanboynz might have a cleaner solution, but this should do the trick for now!