Your friend want to decrease the cooking time of spaghetti noodles by turning up the heat on the stove will this work and why?

No because In a pot on a fire, the surface of the water will be as low as maybe 80 or 90 degrees, when bubbles raise at the bottom, but do not reach the surface yet. (Again here: heat transfer by bubble evaporation is extremely fast, same reasons as for condensation) 10 or 20 °C less are a lot when cooking noodles (wheat starch) this may lower the reaction rate to half the value at 100°C, or even lower (rule of thumb for such reaction

Bis the answerhope it !