@Hapigrlca ...
Spider plants have underground storage structures for water. The older the plant, the more numerous and 'fatter' they will be. This is how the plant survives long periods without being water.
As Kittiana said, having them popping above the soil generally means that the plant has outgrown the pot. You know it's getting tight when the plant starts throwing out plant-lets at an alarming rate! You have several options at this point.
1) Move it into a larger pot. You eventually reach the point where this is no longer practical
2) Cut some of the fat roots off of the plant and re-pot in the same container.
3) If the plant is large enough, you could split it, with each piece having some of the fat roots.
Sometimes, what will happen is that the plant keeps growing and eventually ends up with a couple of inches of stalk between the soil surface and the first leaves. It's definitely time to re-pot when this happens.
As a matter of course, I re-pot all of my spiders every other year. This year, all of my plants are full of babies. When this happens, I tend to cut them all off, take them to work and throw them on the break table. They disappear fast!
