Why is it that some peoples vein pop so much?

Depends on cause: Varicose veins sometimes make veins 'pop' or become noticeable on the skin surface. These veins often look abnormally 'twisty' or like odd bulges on the skin surface. Sometimes veins bulge to help us regulate body temperature, like after exercise or when it is hot outside. And, sometimes they appear to 'pop' out because the person has less body fat or soft tissue - weight lifters are an example.