Electrons in ultrapure crystals stop being a swarm of particles — they flow like a liquid. This picture was proposed back in the mid-20th century by Landau. However, recently physicists noticed: in a strong magnetic field, the resistance of this electron gas changes in jerks, as if the liquid alternately freezes and thins. The reason is that the current heats the flow unevenly — in the middle of the channel, where the speed is higher, viscosity changes more. According to numerical models, in a weak field, the electron ketchup becomes thinner when accelerating. But in a strong field — it first hardens, like wet sand, and then thins even more than before. The same mechanism governs matter in white dwarfs, where an increase in entropy leads to similar viscosity jumps. It was these jumps that Boltzmann once explained through the tendency toward disorder. This discovery overturns the view of quantum fluids — it turns out that the laws of Newton are powerless here. And in the future, such nonlinear effects will help create ultrasensitive magnetic sensors and, perhaps, control magnetic processes in electron flows.