What was the source you were playing? Is your Sonos software up to date on both your controller device and speakers? Which speakers did this sound come from? Did you submit a diagnostic to Sonos, so they could look in to the hard data?

Source: Apple Music

Updates: both controller & speakers updates current

Speaker Source: I believe the Arc Playbar

Diagnostic; Submitted

Now that you’ve submitted a diagnostic, you need to call Sonos Support directly to discuss it.

As noted in the Diagnostics - How do they work? thread, they won’t look at it unless you contact them directly. 

I shall and thank you very much 

I think I may have just experienced the same thing. I was streaming music to my Arc + Sub + Era 300s setup from my music library on the Sonos app. The music began cutting out and it was accompanied with little pops. So I switched to streaming the same music directly from the Apple Music app via AirPlay. Same problem. After I stopped the music, I heard an extremely loud bang from the left surround speaker. It sounded like a bomb went off in the corner of my room. Not good.

I’m assuming, with your experience, you ran a diagnostic, and will be contacting Sonos support, so that the cause can be tracked down. 

After two call with Sonos technicians (level 1 then level 2), the level 2 tech requested I capture the blast while running the diagnostic tool. After explaining to the technician that the blasts are intermittent and would require me to constantly be running diagnostics, no way.

Once she understood, we went thru a factory reset and we shall see if that exercise clears up the problem. I shall report back. 

You capture the last 10-15 minutes of internal activity with a diagnostic so if it is possible to collect one in that time period it might prove helpful.