What are the ramifications of backing out of rea estate transaction before closing? We didn't make any contingencies about 'upon finding a new home'

You have not said whether you are the buyer or the seller. In either case, you would be breaching the contract and would owe the other side either performance or damages. If you are the seller, the buyer could force you to sell. If you are the buyer, the seller could sue you for damages, which would be the loss he or she suffers from a delay in selling and potentially a smaller price. You would be risking a lot. You might want to ask what it would take to get them to let you out and be willing to pay a not insignificant sum. Good Luck.