10/11/2012 at 11:00 AM EDT
Big-name stars showed up to the Roundhouse club in Camden, London, on Sept. 24 to catch a concert by folk-rock band Mumford & Sons: Gwyneth Paltrow
, Chris Martin, Carey Mulligan (who is married to the band's frontman, Marcus Mumford). But no one caught the attention of the crowd – or the band – quite like Adele
. The very pregnant pop star was in the crowd with her boyfriend Simon Konecki and, according to an audience member, was "happily singing along." Even Mumford himself couldn’t ignore her presence. "Marcus name-checked her from the stage," says the audience member, "and she gave a little wave."
That date night with her boyfriend was a rare public appearance for the very private superstar, who all but vanished from the spotlight after winning six Grammys in February (plus two BRIT Awards nine days later) for her massive second album, 21. Long before she became one of music's biggest stars, she told PEOPLE, "I don't think I always want to be the one in the front limelight."
So unlike most of her peers, Adele, 24, hasn't toured (she canceled her U.S. and British dates back in 2011 because of a vocal hemorrhage), refuses most interview requests and has made no red-carpet appearances since February (though she quietly attended two awards ceremonies in the spring). And even though she's topping the charts once again with her hot new James Bond theme "Skyfall," she has no plans to change her course. "Adele has no interest in any of the parties and premieres she gets invited to," says a source who knows the singer. "It's just not her thing.'
Her "thing" these days? Getting ready for the birth of her first child ...