Volland gave Bayer a 2-1 lead in the 71st minute, then struck again six minutes later.
With just two minutes to go, Volland found the back of the net for a third time, securing the 4-1 home win for Bayer.
This second straight victory leaves Bayer securely in fourth place with 51 points, five points ahead of sixth-placed Frankfurt.
Hoffenheim defeated Hamburger 2-0 to occupy the fifth position with 46 points, while Hamburger remains in the relegation zone with only 22 points.
Bayern Munich, which is set to host Borussia Monchengladbach later on Saturday, has already claimed the Bundesliga title with five games to spare.
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