"I feel confident that he is the best person to coach our team at this time," Montreal owner Bob Wetenhall told league website cfl.ca. "I am very appreciative of him being willing to make this additional contribution to our franchise. He has the respect of our players as well as mine."
Popp begins his third stint as head coach, having replaced Rod Rust in 2001 and Don Matthews in 2006. He stayed on in the same role in 2007, leading the Als to an 8-10 record.
After winning his debut as head coach, the former Boise State and Colorado coach lost his next three games - including a July 20 home loss where the Alouettes blew a 24-0 second quarter lead on Calgary before falling 38-27.
The historically potent Montreal offense - according to the CFL website - has the fewest touchdowns and net passing yards so far this season.
Last week, Hawkins guided Montreal to a 32-27 win over Edmonton. The Alouettes' two wins under Hawkins came against teams with a combined record of 2-8.
Montreal has a bye week August 2, and returns to action August 8 at home against Toronto.