Dumb Quest : Amp Clips Or Speakers Blow Up First?

I was reading in another thread somewhere here on Bryston amps that go into clipping when driven hard. How do we know if the speakers can take it when we crank up the volume to earth-shattering levels? In most cases, distortion will kill the drivers of the speakers when listening to insane levels but how do we know if the amp will clip first, or the speakers will blow up first? Do we need any measuring tools or device to measure on how loud can the system go before something burns?

And what does clipping mean? I am guessing the amp will shut down itself. Will the amp blow up into flames of fire? What is normally replaced inside the amp when it has clipped? My amp never clips before so maybe I'm not cranking up the volume loud enough. Most of the time my ears fail first before my equipment do, so it is unlikely I will experience any amps clipping or worse, the speakers blowing up. That's a real nightmare if my speakers would blow up.