Are you wondering what the most popular song of 2015 was??? Well, first off take a wild guess. If you guesses Adele’s new hit single “Hello”, then you were right!.After disappearing for a couple of years, Adele came back with her most popular song yet. Her song “Hello” gained an astonishing 27 million views in 24 hours!!!! She is the musical sensation of 2015, and 2016.