Jumper cables started smoking, meleted entire insulation, WHY?

No its not improper placemnt of the cables.Its cheap thin cables that cause the overlaid making them smoke and melt. Like someone mentioned ,if you connect the cables improperly ,you’ll get a large spark . Therefore you wouldn’t continue to charge the battery ,you’d quikly remove the csbles,or I had hope you would. Because after not removing them you would have damaged something in the car lewvig it undeniable unchangeable until issue was fixed. So they hooked the cables up correctly.