The superheated liquids are metastable with respect to their vapour, what means they can exist under arid conditions whatever the temperature: capillary liquid extracted from arid soils (desert shrubs, Mars sub-surface, ...), solutions in the deep Earth crust, or water involved in rapid disequilibrium events (terrestrial or submarine geysers). The superheating state changes the solvent properties of liquids, and so modifies phase transitions (solid-liquid, liquid-vapor) P-T-X conditions. The synthetic fluid inclusion (SFI) enables to fabricate micro-volumes of hand-made liquid dispersed inside quartz, which readily superheat. Volumes of SFI are intermediate between macro-systems, in which superheating is restricted to around -30-35 MPa with very short lifetime, and nanosystems, wherein confinement effects predominate and in which the host size is similar to the one of the critical nucleus of vapour phase (huge nucleation barrier). This volume-to-metastability relationship is still to be defined quantitatively, and we are targeting to combine thermometric classical measurements with spectrometric characterizations, enabling to establish the threshold between micro- and nano-systems precisely. Meanwhile, the experiments performed so far illustrate the diversity of contexts and situations that could be impacted by superheating issues.