The behaviour of a long-tailed surfactant (Triton X-405) at the water-octane interface was monitored in-situ during microwave heating in the presence of an electrolyte (NaCl). The interfacial tension and bulk temperature were analysed during and after pulsed microwave irradiation. The energy concentration at the interface, which we propose affects the molecular behaviour at the interface, was characterised by a dimensionless number recently proposed by our group. Although the non-ionic surfactant layer was stabilised by the electrolyte solutions, rapid changes to the interfacial conditions, particularly the movement and desorption of surfactants at the interfacial layer, were triggered by pulsed (short, intermittent) irradiation of high microwave power. The dimensionless number, which incorporates both interfacial and bulk properties, can be used as an effective indicator for determining the heating behaviour by accounting for the ability for energy to dissipate through the bulk solutions. The results can be useful to determine an optimal condition for a rapid disruption of the surfactant layer without causing boiling at the interface, making it possible to target conditions desirable for the de-emulsification process.