Understanding the behavior of supercooled water is one of the most interesting open questions in the physics of liquids. Widespread interest dates back to the mid '70s, mainly as a result of the bold proposal that several thermodynamic and transport properties of supercooled water diverge at -45°C. Two scenarios have been proposed to interpret the anomalous increases in the response functions of supercooled water: the existence of a continuous stability boundary, or of a second critical point. A recently proposed extended van der Waals theory and a lattice model with strong orientation-dependent interactions suggest that these interpretations are not mutually exclusive. The generality of these models suggests that similar anomalies may occur in other network-forming liquids, such as SiO2.