Not sure what that implies - did they mean a boom like concrete suddenly breaking or an explosion-type 'boom'?
Anyway, I guess it's best left to the experts and the authorities to work it out.
As an aside, it has intrigued me in the past how US and European high-rise buildings use different construction techniques, and so have entirely different failure-modes. Grenfell didn't collapse the way the WTC did - which some crazy people took as more evidence for their 'inside job' conspiracy-theories about 911 - but I gather that's in reality because the latter used the US style of a steel-frame with concrete 'hanging' from it, so it collapsed becuse the heat made the girders soften to the point where they coudln't support the weight of the concrete floors, causing them to collapse like a house of cards from the top floor downwards (each floor falling forcefully onto the floor below it, causing a successive collapse).
European high buildings like Grenfell are, apparently, more likely to be constructed as a series of concrete panels, each supported on the ones below, and so held up by compression rather than suspension. That's not suspectible to the 'fire weakening girders makes whole thing collapse' type failure that happened with the WTC. But it's also why when I was looking at flats in such buildings, none of them had gas heating (which put me off, as electric heating is much more expensive).
Ronan Point (famous high-rise disaster of a few decades ago) collapsed because a gas explosion in a lower floor blew out the walls, leaving everything above that point unsupported, causing the whole thing to collapse, so ever since that disaster they stopped using gas in such buildings. US high-rises are not susceptable to that kind of failure, but instead they can fail the way the WTC did (though I heard a suggestion that happened becuase they didn't get the heat-insulation on the girders right when constructing it). Seems like either method can suffer catastrophic failure, just of very different forms for each one.
Of course I don't know what kind of construction this particular condo used - as it's not a skyscraper, maybe it didn't use the steel-frame method of the likes of the WTC anyway? How the collapse came about is presumbaly critically-dependent on what kind of construction method it used.