Wholesome jigsaw puzzle youtuber Karen Kavett recently did a challenge where she assembled a 1000 piece puzzle by selecting 100 pieces at random at a time. For a while, this just looked like a bunch of scattered pieces with only a few connections. But once she had 700 or 800 pieces, the whole puzzle started to come together, despite the gaps.
I found this fascinating, because it is a live demonstration of a concept in physics/math: the percolative transition. This is something I often think about when assembling puzzles.