If I plant tiger lilies in a pot instead of in the ground will they come back next year?

They should come back next year as long as you allow the foliage to go dormant naturally and dry out when winter is coming. This will allow the bulbs to absorb nourishment for next season's bloom production. If you live in a REALLY cold location, you might consider moving the pot to the garage for the winter. And probably water it once in a while because the bulbs would receive moisture if they were planted in the ground.