Thousands had paid around £60 a ticket to see the show at the SSE Hydro, which started off well with Clapton and his band, which included Andy Fairweather-Low and Paul Carrack, running through some blues standards and a handful of Clapton's own hits, such as Layla and Tears in Heaven.
Near the end though, as the band launched into JJ Cale's Cocaine, they only got a minute or two into it before Clapton unslung his guitar and made his way off the stage. The rest of the band, seemingly taken by surprise, followed suit.
After two minutes, the musicians returned, Clapton saying briefly: "Sorry about that."
The band abandoned Cocaine and played what turned out to be the final number, High Time We Went, with Carrack taking vocals.
The song over, Clapton picked up his jacket and walked off stage without so much as a 'goodnight'.
As the house lights went up, there was a chorus of booing from the audience.
It is not known what caused Clapton's strop though it may have had something to do with the sound. Some fans reported hearing an echo at the rear of the hall for parts of the show.
One confrontation near the mixing desk saw a male fan in a Clapton tour T shirt argue with a steward who asked him to quieten down.
Several fans at the venue spoke loudly of demanding a refund. Stewards had to deal with a large number of upset customers but were powerless to placate them.
It was a sobering and entirely unexpected end to what had earlier been a fine concert.
The energetic Scottish support act, Hunter and the Bear, had earlier described Clapton as "one hell of a headliner", and so it turned out.
One fan who was at the gig, Matthew Waddell, 18, posted on social media: "Absolutely disgraced at Eric Clapton for leaving the stage halfway through the set without word of warning or anything and for the Hydro for not saying WTF was happening!"
Another angry fan at the concert said: "I've been going to see this guy for 15 years and I've never seen anything like this.It's f***ing ridiculous that he should walk off the stage like that. It was real toys-out-of-the pram stuff."
A female fan in her 30s, who spoke with a Dutch accent, said she and her companion did not understand why a major star like Clapton should have terminated a concert so abruptly.
Soon after, the Hydro's Facebook page was alive with comments from highly irate customers, who all said they felt short-changed.
One, Wojtek Sromek, said bitterly: "For a guy who travelled across half Europe to see Clapton at the SSE I feel truly unsatisfied.
"I believe some explanation is necessary if you want people to treat you seriously."
June Ramsay said: "I never post on FB but I cannot say how disappointed I am - no explanation which (for us was) definitely required.
"I live in Glasgow so only had to lay for tickets - which were dear enough - but totally feel for people who had travelled from all over to see him."
Someone called Glasgow John hit out: "A disgrace Clapton acting like a spoilt wean throwing the dummy oot the pram. Everyone should demand a refund."
Carrel Hendrie told the Hydro: "Think we are due an explanation as to what happened tonight. As it is there was no announcement made in the arena to apologise. No apologies on Facebook, Twitter or your website...poor customer relations. Are we due a partial refund?"