What the hell just happened!?

[Nate's Alero]

So i was taking my alero for it's weekly drive around the block when i decided i wanted to take it on a large trip to just get everything going after sitting for a couple months. So took it on a 100 mile round trip through NH and Maine. When i got back to NH i was going to exit the highway and enter a traffic circle, and it was congested to i WOT'ed off the exit ramp to get into traffic, when i did that it revved to 6,200 RPM and then made a LOUD bang like the engine had just blown itself a new ahoe... It them proceeded to misfire like it HAD blown, and would die when i took my foot off the gas, (i also SWEAR i heard metal hit the road) so i was just trying to limp it home but i saw no smoke, oil stains or heating up.... all of a sudden it started running perfectly like nothing ever happened, no heating up, no leaks, no running rough, nothing seems to be missing from the engine, what the hell happened? Someone want to enlighten me? the SES was already on and i know it started blinking for a minute. i just drove it to work to further see if it HAD blown the engine, and it's fine, it just stinks because of a bad Upstream O2 sensor. The tranny shifts smooth as silk, and it has tons of power (i WOT'ed again getting onto the highway on my way to work) Other then that no loss of oil, no loss of coolant and it's running right at 196*F.... what the hell did i break?