Put the sugar and syrup into a saucepan and stir together to mix. You can't stir once the pan's on the heat, though.
Place the pan on the heat and let the mixture first melt and then turn to goo and then a bubbling mass the color of maple syrup - this will take 3 minutes or so.
Off the heat, whisk in the baking soda and watch the syrup turn into a whooshing cloud of aerated pale gold. Turn this immediately onto a piece of baking parchment or greased foil.
Leave until set and then bash at it, so that it splinters into many glinting pieces.