A nozzle assembly for encapsulating a gaseous solution in bubbles comprises a discharge tube having a diffuser and a foam solution spray nozzle mounted therein. The discharge tube has upstream and downstream ends. The discharge tube has a front face at the upstream end with a first opening configured to be joined to a gas supply line that provides a gaseous solution and a second opening configured to receive a non-expanded foam solution. The downstream end of the discharge tube is open. A chamber is formed within the discharge tube to receive the gaseous solution at the upstream end and release the gaseous solution through the diffuser into the discharge tube towards the downstream end.