Jurgen Klopp's side ran out comfortable winners at the Allianz Arena in the Audi Cup on Tuesday thanks to goals from Sadio Mane, Mohamed Salah and Daniel Sturridge.
Sections of the home support booed the team in the closing stages as they slumped to arguably their lowest point in a difficult pre-season in which they have lost five times in seven matches.
And Hummels, who signed from Borussia Dortmund last year, says it was his toughest game yet.
"We made it far too easy for Liverpool, and it was the worst game that I had ever experienced at Bayern," said the Germany international.
Bayern fans were similarly unimpressed as they watched their side lose 2-0 to Napoli on Wednesday, although Hummels feels the booing was misdirected given that Carlo Ancelotti had named a largely inexperienced team.
"Looking at who was on the pitch, the boos were badly timed," said Hummels.
"Let's put it this way: perhaps it's taken them 20 hours and they were still upset after yesterday. We have to accept that.
"Sometimes it's good to get a shot across the bows but we've had two or three and that's enough now, otherwise it'll be a really difficult August."
Bayern face Borussia Dortmund in the DFL-Supercup on Saturday before they face Chemnitzer in the DFB-Pokal a week later.