Gwen Stefani‘s not just a girl anymore! The 51-year-old singer, who has built a career for herself in music, fashion, and television, appeared on Monday’s “Jimmy Kimmel Live!” where she was asked about the possibility of returning to the band that made her famous — No Doubt.

“When the Tragic Kingdom had its 25th anniversary… it was actually quite nostalgic to watch everybody posting,” Stefani said of last year’s anniversary of No Doubt’s third studio album. “I didn’t know I was going to feel like that. It was kind of depressing. It was kind of nostalgic. It was a very strange feeling.”

She noted that the album was written when she was going through a painful breakup with her No Doubt bandmate, Tony Kanal.

“It started with me and my brother in this band together and then slowly we had different members coming, one of them being my boyfriend for all that time. That ended up being the whole purpose for the Tragic Kingdom is the breakup, the heartbreak,” she said of the end of her seven-year relationship. “There’s a lot of feelings. Even that record, when you say ‘tragic kingdom,’ my heart still kind of is, like, broken. Those songs were about a really sad time for me.”

The group has reunited several times, most recently in 2014 to perform at the Global Citizen Festival. Their most recent album is 2012’s Push and Shove, but in 2013, the group decided to go on hiatus.

“I have no idea what the future is with the band,” Stefani admitted to Kimmel. “I never would have imagined that we would have put the 30 years into it that we did in the first place, you know?”

Last week, Stefani was once again asked about a potential No Doubt reunion with the 30th anniversary of the band coming up next year.

“It is a really big deal,” Stefani told Zane Lowe on Apple Music. “I’m reflecting so much on all the music. When you’re writing new music, reflect on everything that you’ve done. For sure, surreal to think that that happened so long ago. I have no idea what the future holds with that. You know what I mean? It’s impossible.”

More from ET:

Gwen Stefani Talks Falling for Blake Shelton After ‘Such Devastation’

Gwen Stefani Says She Wanted Blake Shelton to Propose Sooner

Gwen Stefani Recreates ‘Hollaback Girl,’ Iconic Looks in New Music Vid