How Do You Display 5-Star Reviews In Google Search Engine Results Page?

In episode 270 of Semantic Mastery's weekly Hump Day Hangouts, one viewer asked how to display 5-star reviews in the Google search engine results page.
The exact question was:
Hi gang! How do you get the 5 stars that show up in some Google searches, it seems to be random but I've never been able to accomplish this.
