The two loaves in this photo are identical twins.  They both suffered near-fatal overproofing (we went to lunch at the CIA, had wine, saw no reason to move quickly, got home late to find loaves spilling over the edges of the proofing basket).

The difference between the two is that I scored the loaf on the left, and I left the loaf on the right.  Since the loaves were already fully proofed, the slashed boule fell and the the unslashed one sprang a bit to its maximum without rupturing the crust.   I prefer the unslashed look in this case.

So I shaped a sourdough boule last night and put it in the refrigerator. This morning when I took it out, this is what I saw:

Any idea why I might have gotten that blowout on the left side? I shaped carefully with good surface tension. Could I have let it bulk ferment too long (~9 hours) before shaping?