Help with melting sugar on a gas stove- heating at low temp just evaporates the milk, and a higher heat burns the sugar

Have made Russian fudge for many years but my new flat has an old gas stove that doesn’t heat pans evenly. Trying to melt sugar and milk over a low heat resulted in the milk drying up and leaving sugar unmelted. Using a medium-high heat just dried up the milk faster and toasted the sugar without melting the granules