Fundamentally, momentum conservation is linked to invariance under space translations. See Noether's theorem. If you want to find a system that does not conserve momentum you should look for situations where space is not uniform, e.g. balls rolling on the surface of a bowl, a planetary system (when the dynamics of the sun is neglected), etc.
Socorro is a city in Socorro County in the U.S. state of New Mexico. It is in the Rio Grande Valley at an elevation of 4,579 feet (1,396 m). In 2012 the population was 8,906.
But as the industry disappeared, Ciudad del Carmen's population boomed to more than five times its size at the time of Ixtoc -- officials peg the city's population today at 150,000. Many of those residents moved to town from other countries and other parts of Mexico to work for Pemex or its contractors.