Usually, when a performer visits a late-night talk show, he or she is there to plug a new project and maybe shoot the breeze over a few funny stories with the host.

But in the case of Killer Mike, of the hip-hop duo Run the Jewels, he made his six minutes and 35 seconds really count when he stopped by "The Late Show" on Tuesday night. Instead of talking about his music, he used his time to shed light on the importance of mentoring, the ongoing problems with race relations in this country, and why Sen. Bernie Sanders...