A method that I have used to bulk up a yarn is to crochet a length of chain stitch. Yes, it does take time. I crochet the length while watching TV.
Items made using Super Bulky yarns are very popular. The earwarmers, the cowls, hats etc.
The following pictures show the yarn used. Patons Big Boucle is the thin strand and the thicker one is after it has been crocheted in chain stitch using a 10 mm crochet hook.
The Ear Warmer used approx 30 yds of chain.