St. Louis-based singer Tish Period never expected her evening performance to turn into a life-changing moment. While covering TLC’s 1995 hit “Waterfalls” at Broadway Oyster Bar, she suddenly found herself face-to-face with the very artists who made the song famous. Rozonda “Chilli” Thomas and Tionne “T Boz” Watkins had just finished performing at Evolution Festival in Forest Park on Sunday, Sept. 28. “We’d just performed, and we were in the van coming here and were like, ‘Wait a minute, we hear our song,’ ” Chilli said in the Instagram video. “I literally thought I saw a ghost,” she told the St. Louis Dispatch.