Pour the sugar and water into a saucepan and bring to a boil over medium heat. Do not stir, and allow the mixture to cook until it caramelizes and turns a deep golden color.

Meanwhile, prepare a loaf baking tray lined with parchment paper.

Once the caramel is ready, carefully pour it into the prepared tray. Immediately sprinkle the baking soda over the caramel and quickly stir using a wooden stick.

The mixture will rapidly expand and rise, forming a light, airy structure similar to a loaf. This reaction happens instantly. Shortly after, the mixture will settle, but the spongy texture will remain.

Allow it to cool completely before breaking or slicing, then serve.