Sometimes the veins on your feet can become enlarged and pop out of the skin but the good news is that most of the time they are normal.
You have to remember that the skin on your feet is very thin and some of these veins run just above the bone so they can look very prominent.
Also if you are on your feet all the time, the muscles of your feet may require more blood supply causing these veins to bulge.
However if you have large varicose veins around your legs and ankles. In these cases those pesky enlarged veins on your feet may actually be abnormal varicose veins.