Can a house be sold before liens are realized?

My father passed away about a year ago. Since then my uncle became executor on our behalf, hired a lawyer, and put our home up for sale. The house was finally sold about 2 months ago, but only then did we become aware there were liens on the house. The house is sold and no longer in our possession, yet we have yet to receive any money from the property. Is this legal? Shouldn't this have been taken care of before the sale? I'm clueless as to how this all works but to me it seems odd. Any advice appreciated!