Identifying bubbles with absolute certainty may be impossible, but identifying them with a reasonable amount of confidence is possible. They follow similar paths.
Of course, there's the old saying that the financial media has correctly predicted 20 of the last 3 bubbles
I think the original quote is "The stock market has forecast nine of the last five recessions." 1966 https://en.wikiquote.org/wiki/Paul_Samuelson But the idea probably applies to most predictions :)
Do you have a data model you can share that would show "a reasonable amount of confidence"?