The local county government can put a lien on your real property for failing to pay your property taxes, in some places, even for not mowing your lawn (an exaggeration of property maint. codes). In Texas, investors can buy a "Tax Deed" at auction. The property owner has two years to buy the lien back, for a defined price, IIRC the taxes owed + 50% for each year. After the 2 yr repayment window, the purchaser of the tax lien gets the title to the property.

http://www.nuwireinvestor.com/articles/how-texas-tax-sales-w...

http://www.dallascounty.org/department/pubworks/documents/St...