What is the Elemental Chaos?

What is the Elemental Chaos like visually in D&D 5e?

The DMG more or less covers the air, water, earth, and fire planes but says nothing on the Elemental Chaos nor what it’s like. My only guess is that it’s something like Limbo, both being pure-ish (Limbo has some patches of unchangeable bits) chaos. If 5e hasn’t covered this topic at all, I’m open to lore from the most recent edition on this topic.